1. Field of the Invention
This invention is related to access control of wireless medium used in streaming of time sensitive data such as real-time Audio-Visual data for interactive applications, communicative applications and gaming. In order to meet Quality of Service of the communication session set-up between mobile wireless terminals (or stations) and between access points or base stations and mobile terminals, a network layer that has control over an access mechanism need to aware on how the Quality of Service required for the session need to be served. The need to maintain service level for transmission of real-time data between access points and mobile terminals becomes increasingly as the number of mobile terminals and data traffic within the control of the access point increases.
2. Description of the Background Art
In some of wireless local area network (LAN) in compliance with IEEE 802.11, for example, it uses common wireless medium to exchange critical control and connection information (i.e. information on Quality of Service) between Station (STA) and the access point (AP). The control and connection information is exchanged in the form of management frames that happens periodically or on-demand depending on the data delivery requirement of the STA or the AP at any point in time. Critical and none critical data exchange between STA and AP is performed through contention of wireless medium. This makes predictability of critical data exchange difficult thus making real-time data streaming over the wireless medium almost impossible.
In most networks, Quality of Service provided for a data streams is largely handled at the Internet Protocol (IP) or application layers. In order to be more effective in assuring the Quality of Service for the data stream can be meet under all network conditions in a wireless network, it becomes necessary that the layer 2 (or medium access controller) whose responsibility is to manage accesses to the wireless medium has control over access mechanism. In the present invention, the purpose is to offer higher layer some control over how the Quality of Service of the data connection can be guaranteed.
The other problem, the present invention seeks to solve is the reduction of required delay bound faced by the medium access controller of the wireless medium. In most real-time audio-visual delivery, persistence connection to the wireless medium is mandatory. In some cases, the time for which audio-visual data is held by the Medium Access Controller (MAC) must be constant and must be within a specific time. If the holding of the real-time data exceed the maximum time for which the data is allowed to stay in the MAC layer, the real-time delivery characteristic required is no longer meet the criteria.
In some of the wireless networks, medium access is largely based on data streams pumped from upper layers to the MAC layer in an ad-hoc basis. Assignment of wireless medium access in most cases follows an ad-hoc basis. For real-time critical data streams, there are needs to have a guaranteed time slot for the wireless medium access such that the data packets from the data streams can be delivered in a timely fashion. This invention provides a mechanism to allow upper register data streams with the MAC layer such that the medium access time can be guaranteed for the delivery of the data streams.
In the process of contending for wireless medium for all data stream delivery using prior art, both management and user data used the same medium access channel. This increases probability of having a collision in the wireless medium as the number of station controlled by the central access point increases. The present invention provides a different channel for station to contend for the right to register a data stream an exclusive time slot for the registered data stream delivery. The present art further provides a dynamic mechanism to allocate time slots for station to contend for registration of data stream for exclusive channels. Using a separate time slot for different data exchange, it provides a better bandwidth allocation for control data exchange between the central access point and the stations.
In the prior art, data delivery from the upper layers will contend for wireless medium and wasted a large amount of bandwidth on collision. The present invention allows data streams from the upper layers to have connection-oriented features in the wireless packet network.